1. Field of the Invention
This invention relates to an electronic endoscope system comprising a flexible conduit or elongated scope having a solid state image sensor provided at a distal end thereof, to generate image-pixel signals; a video-signal processing unit, to which the flexible scope is detachably connected at a proximal end thereof, to produce a video signal on the basis of the image-pixel signals; and a TV monitor for reproducing an image in accordance with the video signal.
2. Description of the Related Art
In such an electronic endoscope system, a CCD (charge-coupled-device) image sensor is usually utilized as the solid state image sensor, and is associated with an objective lens system provided at the distal end of the flexible scope. Also, a flexible optical guide, formed as a bundle of optical fibers, is extended through the flexible scope, and is associated with a lighting lens system provided at the distal end of the flexible scope.
On the other hand, the video-signal processing unit includes a white-light source, such as a halogen lamp, a xenon lamp or the like. When the flexible scope is connected to the video-signal processing unit, the proximal end of the optical light guide is optically connected to the light source. Thus, an object image to be photographed is illuminated by light radiating from the distal end of the optical light guide, and is focused as an optical image on a light-receiving surface of the CCD image sensor by the objective lens system.
The focused optical image is converted into a frame of analog image-pixel signals by the CCD image sensor, and the frame of analog image-pixel signals is read from the CCD image sensor. The reading of the frame of image-pixel signals from the CCD image sensor is successively performed at a given regular time-interval, and the successively-read frames of image-pixel signals are fed to the video-signal processing unit, in which the frames of image-pixel signals are suitably processed, thereby producing a video signal including image-pixel signals and various synchronizing signals. Then, the video signal is fed from the video-signal processing unit to the monitor to reproduce the photographed object on a screen of the monitor in accordance with the video signal.
As is well known, the CCD image sensor, used in the electronic endoscope system, has a smaller size than that of a CCD image sensor used in a usual TV camera. Namely, a number of image pixels, included in one frame, obtained from the former CCD image sensor, is less than a number of image pixels, included in one frame, obtained from the latter CCD image sensor. Nevertheless, in the electronic endoscope system, the monitor having a usual standard size is used, and thus an object photographed by the CCD image sensor is only reproduced and displayed on a partial area of the screen of the monitor.
Note, in reality, although a video signal is produced and prepared with respect to an overall area of the screen of the monitor, the video signal exhibits a pedestal level over the remaining area of the screen except for the partial area on which the photographed image is only reproduced and displayed.
A size of the reproduced image is sufficient for a scope operator who observes the image at close range. However, when the reproduced image is observed at far range by some persons, for example, medical trainees, the size of the image is too small. Thus, conventionally, an electronic endoscope system has already been proposed, in which an image to be reproduced and displayed on a screen of a TV monitor can be selectively and optionally enlarged to a predetermined size.
On the other hand, in the conventional electronic endoscope system, a CRT controller is frequently incorporated in the video-signal processing unit to produce and display a pointer image on the screen of the monitor. The pointer image is superposed on an image reproduced and displayed on the screen of the monitor, and can be freely moved under control of the CRT controller. Namely, the pointer image is used to indicate a location on the reproduced and displayed image, at which, for example, a lesion occurs. Note, the CRT controller per se is well known in this field.
Conventionally, in a case where the CRT controller is utilized in the electronic endoscope system in which a size of a reproduced and displayed image is changeable on the screen of the monitor, a position of the displayed pointer image cannot be converted in accordance with the size-change of the reproduced and displayed image or displaying-area. Thus, for example, when an originally-sized image, on which a significant location is indicated by the pointer image, is enlarged to a large-sized image, it is necessary to shift and adjust the position of the pointer image on the screen of the monitor before a corresponding significant location can be indicated by the pointer image on the large-sized image. Of course, this is also true for a case where the large-sized image is returned to the originally-sized image.
Therefore, an object of the present invention is to provide an electronic endoscope system as mentioned above, in which a position of a displayed pointer image on a screen of a monitor can be automatically converted in accordance with a size-change of a reproduced and displayed image on the screen of the monitor such that two locations, indicated by the pointer image on two-sized displaying-areas, can correspond to each other.
In accordance with a first aspect of the present invention, there is provided an electronic endoscope system, which comprises: an elongated scope having a solid state image sensor, such as a CCD image sensor, provided at a distal end thereof, to generate image-pixel signals; a video-signal processing unit, to which the elongated scope is detachably connected at a proximal end thereof, to provide a video signal on the basis of the image-pixel signals; a monitor that reproduces an image in accordance with the video signal; a displaying-size changer that changes a size of a displaying-area of the reproduced image on a screen of the monitor to another size and vice versa; a pointer-image generator that generates a pointer image on the screen of the monitor; and a pointer-image controller that controls a shifting of the pointer image on the screen of the monitor. The pointer image controller includes a pointer-image-position converter that converts a position of the pointer image on the screen of the monitor in accordance with the size-change of the displaying-area of the reproduced image on the screen of the monitor, such that two positions, indicated by the pointer image on the two-sized displaying-areas, correspond to each other.
Preferably, the pointer-image-position converter comprises a two-dimensional coordinate system defined with respect to the screen of the monitor, a two-dimensional coordinate generator that generates two-dimensional coordinates representing the position of the pointer image, and a proportional position-convertor that proportionally converts a set of two-dimensional coordinates, representing a position of the pointer image on one of the two-sized displaying-areas, into another set of two-dimensional coordinates, representing a corresponding position of the pointer image on the other-sized displaying-area.
The electronic endoscope system may further comprises a shift limiter that limits a shifting of the pointer image within each of the two-sized displaying-areas. Preferably, the shift limiter comprises a boundary converter that converts a two-dimensional limit range, corresponding to one of the two-sized displaying-areas, within which the shifting of the pointer image is limited, into another two-dimensional limit range, corresponding to the other-sized displaying-areas, within which the shifting of the pointer image is limited, in accordance with the size-change of the displaying-area of the reproduced image on the screen of the monitor.
In accordance with a second aspect of the present invention, there is provided an electronic endoscope system, which comprises: an elongated scope having a solid state image sensor provided at a distal end thereof, to generate image-pixel signals; a video-signal processing unit, to which the elongated scope is detachably connected at a proximal end thereof, to produce a video signal on the basis of the image-pixel signals; a monitor that reproduces an image in accordance with the video signal; a displaying-area changer that changes a displaying-area of the reproduced image on a screen of the monitor between a first-sized displaying-area and a second-sized displaying-area; a pointer-image generator that generates a pointer image on the screen of the monitor; and a pointer-image controller that controls a shifting of the pointer image on the screen of the monitor. The pointer image controller includes a pointer-image-position converter that converts a position of the pointer image on the screen of the monitor in accordance with the displaying-area change of the reproduced image on the screen of the monitor between the first-sized displaying-area and the second-sized displaying-area, such that a position, indicated by the pointer image on the first-sized displaying-area, corresponds to a position, indicated by the pointer image on the second-sized displaying-area.
According to the second aspect of the present invention, preferably, the pointer-image-position converter comprises a two-dimensional coordinate system defined with respect to the screen of the monitor, a two-dimensional coordinate generator that generates two-dimensional coordinates representing the position of the pointer image, and a proportional position-convertor that proportionally converts a set of two-dimensional coordinates, representing a position of the pointer image on the first-sized displaying-area, into another set of two-dimensional coordinates, representing a corresponding position of the pointer image on the second-sized displaying-area.
According to the second aspect of the present invention, the electronic endoscope system may comprises a shift limiter that limits a shifting of the pointer image within each of the first-sized and second-sized displaying-areas. Preferably, the shift limiter comprises a boundary converter that converts a two-dimensional limit range, corresponding to the first-sized displaying-area, within which the shifting of the pointer image is limited, into another two-dimensional limit range, corresponding to the second-sized displaying-areas, within which the shifting of the pointer image is limited, in accordance with the displaying-area change of the reproduced image on the screen of the monitor between the first-sized displaying-area and the second-sized displaying-area.